232 PECULIARITIES IN THE MAGNETISM 
during the time that the hot iron tube was being 
adjusted in its proper place, but soon afterwards 
came to rest at zero, indicating an entire absence 
of magnetic action in the iron ; which did not re- 
appear until the temperature had subsided so as 
to display a moderate degree of redness on the 
surface of the tube. 
59. The needle first indicated a magnetic ae- 
tion in the iron tube by a slow movement of its 
north end towards it, but shortly afterwards its 
motion became.rapid, until it arrived at its maxi- 
mum of deflection, which occurred when the iron 
had fallen to a dull red heat. This maximum of 
deflection continued for a considerable time after 
the iron had cooled to blackness; and was not 
seen to lessen whilst the iron remained unmo- 
lested. 
60. The agitation of the needle during the 
adjustment of the hot tube in the first experiment 
(58), was found to be occasioned by the compa- 
ratively cold tongs, by which the upper end of 
the iron was held ; and was avoided in all the sub- 
sequent experiments by applying the tongs to the 
middle part of the hot iron: under which circum- 
stances not the slightest movement of the needle 
